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RR Lyrae
RR Lyrae Distance to Pluribus: 1,222 LY Distance to Sol: 848 LY Union Star System The RR L system contains two planets (Jovian type). The planets are RRL One and RRL Two. Both planets are occupied and utilized for fuel production. In addition to the planets, there is a very old (constantly updated and expanded) space station. It was established by United Earth even before Union membership. Variable stars were of great interest to Earth science and also utilized for Navigation purposes. The station RR-Lighthouse transmits one of the Navigation Pings to which Nav Systems can be calibrated or manual Nav calculations can be performed. is a variable star in the Lyra constellation, located near the border with the neighboring constellation of Cygnus. As the brightest star in its class,it became the eponym for the RR Lyrae variable class of stars and it has been extensively studied by astronomers. RR Lyrae variables serve as important standard candles that are used to measure astronomical distances. The period of pulsation of an RR Lyrae variable depends on its mass, luminosity and temperature, while the difference between the measured luminosity and the actual luminosity allows its distance to be determined via the inverse square law. Hence, understanding the period-luminosity relation for a set of local RR Lyrae-type variable stars allows the distance of more distant stars of this type to be determined. This type of low-mass star has consumed the hydrogen at its core, evolved away from the main sequence, and passed through the red giant stage. Energy is now being produced by the thermonuclear fusion of helium at its core, and the star has entered an evolutionary stage called the horizontal branch (HB). The effective temperature of an HB star's outer envelope will gradually increase over time. When its resulting stellar classification enters a range known as the instability strip—typically at stellar class A—the outer envelope can begin to pulsate. RR Lyrae shows just such a regular pattern of pulsation, which is causing its apparent magnitude to vary between 7.06–8.12 over a short cycle lasting 0.56686776 days (13 hours, 36 minutes). Each radial pulsation causes the radius of the star to vary between 5.1 and 5.6 times the Sun's radius. This star belongs to a subset of RR Lyrae-type variables that show a characteristic behavior called the Blazhko effect, named after Russian astronomer Sergey Blazhko. This effect is observed as a periodic modulation of a variable star's pulsation strength or phase; sometimes both. It causes the light curve of RR Lyrae to change from cycle to cycle. As of 2009, the cause of this effect is not yet fully understood. The Blazhko period for RR Lyrae is 39.1 ± 0.3 days. As with other RR Lyrae-type variables, RR Lyrae itself has a low abundance of elements other than hydrogen and helium—what astronomers term its metallicity. It belongs to the Population II category of stars that formed during the early period of the Universe when there was a lower abundance of metals in star-forming regions. The trajectory of this star is carrying it along an orbit that is close to the plane of the Milky Way, taking it no more than 680 ly (210 pc) above or below this plane. The orbit has a high eccentricity, bringing RR Lyrae as close as 6.80 kly (2.08 kpc) to the Galactic Center at periapsis, and taking it as far as 59.9 kly (18.4 kpc) at apapsis. Distance to Earth: 848 light years Magnitude: 7.195 Luminosity: 49 L☉ Surface temperature: 6,125 K Absolute magnitude (MV): 0.600 ± 0.126 Radius: 5.1 to 5.6 R☉ Category:Solar Systems